Python 如何识别列中的组并将其外部边框

要在CLASS列中的每个组周围绘制一个蓝色矩形，需要为分组的行设置上、下、左和右边框.这需要 for each 组的第一行和最后一行以及整个组设置边框.这可以实现如下所示

import pandas as pd

# Sample data
df = pd.DataFrame({
    'class': ['class_a', 'class_a', 'class_a', 'class_b', 'class_c', 'class_c'],
    'name': ['name_1', 'name_2', 'name_3', 'name_1', 'name_1', 'name_2'],
    'id': [5, 7, 1, 2, 3, 8]
})

def style_border_around_class_groups(df):
    # Get the start and end indices of each group
    start_indices = df.groupby('class').head(1).index
    end_indices = df.groupby('class').tail(1).index

    # Define a dictionary to store styles for each cell
    styles_dict = {}

    # For each row in the dataframe
    for i, row in df.iterrows():
        # Default styles
        top_border = ""
        bottom_border = ""
        left_border = ""
        right_border = ""

        # If the row index is a start index, add top border
        if i in start_indices:
            top_border = "3px solid blue"
        # If the row index is an end index, add bottom border
        if i in end_indices:
            bottom_border = "3px solid blue"

        # Apply horizontal borders to all columns
        for col in df.columns:
            styles_dict[(i, col)] = f"border-top: {top_border}; border-bottom: {bottom_border};"

        # Apply left border only to the first column
        styles_dict[(i, df.columns[0])] += "border-left: 3px solid blue;"

        # Apply right border only to the last column
        styles_dict[(i, df.columns[-1])] += "border-right: 3px solid blue;"

    # Apply the styles
    s = df.style.apply(lambda x: [styles_dict.get((x.name, col), "") for col in df.columns], axis=1)
    return s

# Apply the styling function
styled_df = style_border_around_class_groups(df)
styled_df

这导致了